Frac sand is generally high-purity quartz sand that is added to fracking fluids used in subterranean hydrocarbon completions. The fracking fluids along with the frac sand are injected under pressure into oil and gas wells during the process of hydraulic fracturing or fracking. The high pressure of the fracking fluids on the subterranean hydrocarbon formation causes fractures of the hydrocarbon formation through which the fracking fluids travel carrying the frac sand. The frac sand settles out of the fracking fluid within the fractures and prevents the fractures from closing when fracking fluid pressure dissipates. The fractures, held open by the frac sand, provide hydrocarbons within the subterranean formation a fluid pathway to the oil and/or gas well for production to the surface.
The oil and gas industry has placed heavy emphasis on best-in-class frac sand as being the primary proppant used in unconventional oil and gas well completions. For example, billions of dollars of development capital have been spent on mining and logistics infrastructure to transport superior sand from various regions of the United States to the hydrocarbon producing basins in the United States. The principle sources of preferred sands in the United States, for example, come from the upper Midwest of the United States, such as Wisconsin, and must be shipped by truck or rail to oil and gas plays in Texas, Oklahoma and North Dakota.
With the decrease in hydrocarbon prices in recent years, alternatives to the transportation and logistics of moving Northern White or Ottawa sand from the upper Midwest have been considered to maintain oil and gas margins. Resin coated sands and ceramics offer an alternative to raw quartz sand but at a higher cost than the transportation of Northern White and Ottawa raw sands. Therefore, raw sands from the upper Midwest continue to make up the majority of the proppant market. Many companies have recently invested in west Texas dune sand mines, for example, as a lower cost alternative to such transportation. While less costly transportation and logistics costs of west Texas sands provide strong economic incentives, Applicants recognized that the quality of such sands is questionable.
Applicants also recognized, for example, that under harsh conditions, hydraulic fracturing propping agents, or proppants, such as frac sand, are subject to variables that diminish their effectiveness in ensuring hydrocarbon flow passages and hydrocarbon flow velocity. A desired characteristic of the sand proppants is to be able to withstand high physical pressures such that, when the fracking fluid pressure in the fractures is reduced, the resettling of the formation does not crush the frac sand, thereby closing the fractures and, thus, the fluid pathway for the formation hydrocarbons to travel to surface via the well.